3,499 research outputs found
Odin observations of ammonia in the Sgr A +50 km/s Cloud and Circumnuclear Disk
Context. The Odin satellite is now into its sixteenth year of operation, much
surpassing its design life of two years. One of the sources which Odin has
observed in great detail is the Sgr A Complex in the centre of the Milky Way.
Aims. To study the presence of NH3 in the Galactic Centre and spiral arms.
Methods. Recently, Odin has made complementary observations of the 572 GHz NH3
line towards the Sgr A +50 km/s Cloud and Circumnuclear Disk (CND). Results.
Significant NH3 emission has been observed in both the +50 km/s Cloud and the
CND. Clear NH3 absorption has also been detected in many of the spiral arm
features along the line of sight from the Sun to the core of our Galaxy.
Conclusions. The very large velocity width (80 km/s) of the NH3 emission
associated with the shock region in the southwestern part of the CND may
suggest a formation/desorption scenario similar to that of gas-phase H2O in
shocks/outflows.Comment: 5 pages, 3 figures, 3 table
Impurity-induced dephasing of Andreev states
A study is presented concerning the influence of flicker noise in the
junction transparency on coherent transport in Andreev states. The amount of
dephasing is estimated for a microwave-activated quantum interferometer.
Possibilities of experimentally investigating the coupling between a
superconducting quantum point contact and its electromagnetic environment are
discussed.Comment: 8 pages, 4 figure
Short wavelength quantum electrodynamical correction to cold plasma-wave propagation
The effect of short wavelength quantum electrodynamic (QED) correction on
plasma-wave propagation is investigated. The effect on plasma oscillations and
on electromagnetic waves in an unmagnetized as well as a magnetized plasma is
investigated. The effects of the short wavelength QED corrections are most
significant for plasma oscillations and for extraordinary modes. In particular,
the QED correction allow plasma oscillations to propagate, and the
extra-ordinary mode looses its stop band. The significance of our results is
discussed.Comment: 12 pages, 5 figure
The RHIC Zero Degree Calorimeter
High Energy collisions of nuclei usually lead to the emission of evaporation
neutrons from both ``beam'' and ``target'' nuclei. At the RHIC heavy ion
collider with 100GeV/u beam energy, evaporation neutrons diverge by less than
milliradians from the beam axis Neutral beam fragments can be detected
downstream of RHIC ion collisions (and a large aperture Accelerator dipole
magnet) if 4 mr but charged fragments in the same angular range
are usually too close to the beam trajectory.
In this 'zero degree' region produced particles and other secondaries deposit
negligible energy when compared with that of beam fragmentation neutrons.
The purpose of the RHIC zero degree calorimeters (ZDC's) is to detect
neutrons emitted within this cone along both beam directions and measure their
total energy (from which we calculate multiplicity). The ZDC coincidence of the
2 beam directions is a minimal bias selection of heavy ion collisions. This
makes it useful as an event trigger and a luminosity monitor\cite{baltz} and
for this reason we built identical detectors for all 4 RHIC experiments.
The neutron multiplicity is also known to be correlated with event geometry
\cite{appel} and will be used to measure collision centrality in mutual beam
int eractions.Comment: 18 pages, 12 figure
Metastatic uveal melanoma managed with best supportive care
Non peer reviewe
Vortex Structure in the Plasma Flow Channels of the Venus Wake
An overall description of the solar wind that streams into the Venus wake and the ionospheric plasma that is driven from that planet’s magnetic polar region is examined from measurements conducted with the various spacecraft that have probed the Venus plasma environment (Mariner 5, Venera 9-10, Pioneer Venus Orbiter, Venus Express). It is shown that the plasma properties in the Venus wake describe conditions that are less suitable for steady gyrotropic trajectories of the planetary particles but require the assumption that they are also subject to a fluid dynamic description that introduces structures similar to those generated through kinetic forces. Most notable is that there is evidence of decelerated solar wind proton fluxes measured within plasma channels that are mostly populated by outflowing planetary ions and that the solar wind particles moving in the wake execute trajectories that resemble motion along a vortex shape with motion directed even back toward the planet in the Venus inner wake. The plasma flow channels are mostly restricted to the vicinity of the midnight plane and extend downstream from the magnetic polar region
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